Add `assert_predicate` and `assert_operator`

test/assert.rb

+$undefined = Object.new
 $ok_test = 0
 $ko_test = 0
 $kill_test = 0
@@ -136,6 +137,25 @@ def _assert_include(affirmed, collection, obj, msg = nil)
   assert_true(ret, msg, diff)
 end
 
+def assert_predicate(*args); _assert_predicate(true, *args) end
+def assert_not_predicate(*args); _assert_predicate(false, *args) end
+def _assert_predicate(affirmed, obj, op, msg = nil)
+  unless ret = obj.__send__(op) == affirmed
+    diff = "    Expected #{obj.inspect} to #{'not ' unless affirmed}be #{op}."
+  end
+  assert_true(ret, msg, diff)
+end
+
+def assert_operator(*args); _assert_operator(true, *args) end
+def assert_not_operator(*args); _assert_operator(false, *args) end
+def _assert_operator(affirmed, obj1, op, obj2 = $undefined, msg = nil)
+  return _assert_predicate(affirmed, obj1, op, msg) if obj2 == $undefined
+  unless ret = obj1.__send__(op, obj2) == affirmed
+    diff = "    Expected #{obj1.inspect} to #{'not ' unless affirmed}be #{op} #{obj2.inspect}."
+  end
+  assert_true(ret, msg, diff)
+end
+
 ##
 # Fails unless +obj+ is a kind of +cls+.
 def assert_kind_of(cls, obj, msg = nil)

test/t/float.rb

@@ -82,8 +82,8 @@ assert('Float#ceil', '15.2.9.3.8') do
 end
 
 assert('Float#finite?', '15.2.9.3.9') do
-  assert_true 3.123456789.finite?
-  assert_false (1.0 / 0.0).finite?
+  assert_predicate 3.123456789, :finite?
+  assert_not_predicate 1.0 / 0.0, :finite?
 end
 
 assert('Float#floor', '15.2.9.3.10') do
@@ -139,7 +139,7 @@ assert('Float#round', '15.2.9.3.12') do
   nan = 0.0/0.0
   assert_raise(FloatDomainError){ nan.round }
   assert_raise(FloatDomainError){ nan.round(-1) }
-  assert_true(nan.round(1).nan?)
+  assert_predicate(nan.round(1), :nan?)
 end
 
 assert('Float#to_f', '15.2.9.3.13') do
@@ -178,10 +178,10 @@ assert('Float#divmod') do
 end
 
 assert('Float#nan?') do
-  assert_true (0.0/0.0).nan?
-  assert_false 0.0.nan?
-  assert_false (1.0/0.0).nan?
-  assert_false (-1.0/0.0).nan?
+  assert_predicate 0.0/0.0, :nan?
+  assert_not_predicate 0.0, :nan?
+  assert_not_predicate 1.0/0.0, :nan?
+  assert_not_predicate -1.0/0.0, :nan?
 end
 
 assert('Float#<<') do
@@ -240,9 +240,9 @@ assert('Float#to_s') do
 end
 
 assert('Float#eql?') do
-  assert_true(5.0.eql?(5.0))
-  assert_false(5.0.eql?(5))
-  assert_false(5.0.eql?("5.0"))
+  assert_operator(5.0, :eql?, 5.0)
+  assert_not_operator(5.0, :eql?, 5)
+  assert_not_operator(5.0, :eql?, "5.0")
 end
 
 end # const_defined?(:Float)